Digital cameras and optical imaging devices employ image sensors. Image sensors include an array of pixels, which are unit devices that convert an optical image into digital data. The pixels often manifest themselves as charge-coupled devices (CCDs) or complementary metal oxide semiconductor (CMOS) sensors, such as photodiodes. While CCDs are in some regards a more mature technology than CIS devices, CIS devices offer lower power consumption, smaller size, and faster data processing than CCDs as well as direct digital output that is not available in CCDs. Also, CIS devices have lower manufacturing costs than CCDs since CIS device can be manufactured using many standard semiconductor manufacturing processes. For these reasons, commercial employment of CIS devices has been steadily increasing in recent years.